Okay so I know that having more than one archetype works the following way;
"A character can take more than one archetype and garner additional alternate class features, but none of the alternate class features can replace or alter the same class feature from the base class as another alternate class feature."
So if for example 2 archetype change/remove Alchemist bombs, you can't take both.
But how do this work with Skills for example?
|Taja the Barbarian|
According to the archetype stacking faq adding a single class skill is altering the "class skills" feature.
If the two archetypes touch the same class feature in any way, you can't combine them. In your example, the class feature is 'class skills' so the two archetypes are incompatible.
Note that class skills added from Sorcerer Bloodlines or Oracle Mysteries are usually considered a separate class feature, so an archetype touching Oracle Class Skills does not necessary clash with an archetype touching the Oracle Class Skills from the Mystery: You'll need to read these archetypes carefully.
For example, the following two Oracle archetype features do not clash (thought the archetypes themselves clash on another feature):
Class Skills: A spirit guide gains all Knowledge skills as class skills. This replaces the bonus class skills gained from the oracle’s mystery.
Class Skills: A shigenjo adds Survival to her list of class skills in place of Diplomacy.